CLEMSON, S.C. - Clemson coach Oliver Purnell screamed so much at practice Friday that he lost his voice.

What was the fuss about?

"Defense," Tiger forward Trevor Booker said.

That figures given that a swarming, pressure-packed effort against the ball has kept the 12th-ranked Tigers perfect in two games this week.

The Tigers improved to 16-0 on Saturday when they used a 24-10 second-half run to break free of North Carolina State for a 63-51 win. That followed a 66-59 victory over Alabama on Tuesday, when the Tigers rallied with a 14-0 run fueled by defensive pressure.

Booker led the way against the Wolfpack with 23 points and a dominating presence underneath for the Tigers (2-0 Atlantic Coast Conference).

"I thought our defense was the story with our ability to shut them down early and late," said Purnell, his voice raspy and barely audible.

That's been Clemson's touchstone all season-and maybe the reason there's a good chance to keep their run of success going deep into conference play.

The Tigers are a game shy of matching the school's best start, accomplished in 1986-87 and matched two years ago.

That 2007 club was flashy and potent offensively, but it couldn't sustain that in league play, following a 17-0 opening with a 2-9 run and winding up in the NIT.

Now with Clemson going full-throttle on the defensive side, Purnell's not letting up a bit.

"He yelled at us a good bit," Booker said. "We finally listened to him today."

Still, it took awhile for Purnell's message to get through.

Clemson squandered a 10-point first-half lead and was tied with the Wolfpack (9-4, 0-1) 33-all after Trevor Ferguson's driving bucket.

That's when the Tigers cranked it up, outscoring North Carolina State 24-10 over the next 10 minutes to take control.

The Wolfpack committed five straight turnovers during one stretch and could not recover. Particularly not with Booker, the 6-foot-7 junior, having his way near the basket.

He had 10 points during the run and finished with his highest output since scoring 25 against Presbyterian on Nov. 28.

Booker has a sweet shot from the outside-he's 5-for-11 on 3-pointers this season-but Purnell says his place is underneath.

"I thought he did too much fading until early in the second half. Then he went to work on the block," Purnell rasped. "As long as we can get the ball down low, let's keep doing it."

Clemson probably can't alter its formula if it hopes to keep winning. Next up is undefeated and fourth-ranked Wake Forest next Saturday. Then the Tigers travel to North Carolina, where they're 0-53.

Campus will likely be crazy with hoops talk and dreams of basketball success. Count on Purnell discovering his voice in time to tone down the hype and keep his players grounded.

"We're just playing ball. We're just playing like we're having fun," said K.C. Rivers, who had nine points and 11 rebounds. "We're enjoying what we do like before we were ranked so we're going to continue to do that."

North Carolina State finished with its lowest scoring output of the season, 21 points below its average coming in.

Courtney Fells had 10 points to lead the Wolfpack, whose four defeats have come to ranked opponents.

Booker added six blocks and three steals.

Brandon Costner, North Carolina State's leading scorer coming in at nearly 15 points a game, had nine points on 3-of-9 shooting before fouling out.

Clemson's defense figured to wear down North Carolina State. But the Wolfpack helped out with a major cold spell from the floor. They missed their first seven shots and were just 1-of-15 nine minutes in.

The Tigers didn't fare much better at 2-for-11, which was why they were only up 6-2 after that stretch.

It was Clemson's fourth straight victory over the Wolfpack and the second time in three seasons it has opened the ACC 2-0.

North Carolina State coach Sidney Lowe was pleased with his club's resolve in fighting through the early shooting problems. Once Clemson turned up its defense, though, he was disappointed at his team's reaction.